#include <iostream>
#include <memory>
using namespace std;

class A{
    public:
        A(){};
        ~A(){};
};

int main(){
    unique_ptr<A> p1(new A());
    shared_ptr<A> p2=make_shared<A>();
    shared_ptr<A> p3=p2;
    weak_ptr<A> p4;
    return 0;
}
